Circuit/System Description

Automatic Headlamp Leveling (without Electronic Suspension Control) 

The automatic headlamp leveling system automatically maintains the vertical alignment of the headlamps when the vehicle load and driving conditions change. The vehicle is equipped with suspension height sensors located on the left front and left rear suspensions. Each sensor receives a 5 V reference, signal, and low reference circuits from the headlamp control module. The headlamp control module receives inputs from the front and rear suspension height sensors to determine vehicle pitch. The headlamp control module calculates the difference in vehicle pitch and sends a serial data message to both headlamp leveling control modules located in each headlamp assembly. The headlamp leveling control modules responds by driving their respective headlamp leveling actuators to the position commanded by the headlamp control module.

Automatic Headlamp Leveling (with Electronic Suspension Control) 

The front and rear vertical suspension acceleration sensors provide the suspension control module with suspension position information. Each sensor receives a 5 V reference, signal, and low reference circuits from the suspension control module. The vertical suspension acceleration sensors are connected to each control arm of the front and rear suspensions. As the vehicle travels, the suspension compresses and rebounds moving the vertical suspension acceleration sensors. This causes the signal output of the sensor to change. The suspension control module compares the information from all four vertical suspension acceleration sensors and adjusts the suspension as needed. The suspension control module communicates the suspension positions with the headlamp control module via serial data. The headlamp control module uses the suspension position sensor information received from the suspension control module to calculate the difference in vehicle pitch and sends a serial data message to both headlamp leveling control modules located in each headlamp assembly. The headlamp leveling control modules responds by driving their respective headlamp leveling actuators to the position commanded by the headlamp control module.